Believe it or not, I don't think that any of this is font. This piece seems to be created by Dana Tanamachi, an artist and graphic designer who works exclusively in chalk. Don't know if this link will show up, but I found the story about her (along with a picture of the piece) here --> http://online.wsj.com/article/SB10001424052970203458604577265453430025274.html?KEYWORDS=dana+tanamachi#
Being a competitor of Dana's I've researched this font as it's one of her most used. I actually make an effort not to use so I don't get my work confused with hers. You can almost pull the entire alphabet of it from all of her different sample images. Most notable are the S and the Q and the lower case x, they are dead on ENGRAVER'S SCRIPT. The rest of this main script font she uses so often is her take on engraver's script as well. While I don't think there is an exact font called that, I find it often in my old typography and lettering books, it's plate 25 of 60 Alphabets by the Hunt Brothers, 4th printing.
You can find several similar fonts by looking up copperplate script fonts:
She draws it single line and then comes back and thickens up all of the downward strokes. Then she drops in a shadow line, normally to the bottom right. If you want a quick trick for getting the shadow line right draw your letters out first. Then tape two pieces of chalk together, hold them in your hand at a 45* angle facing down and to the right, then trace over the right side portions of the letters lightly. Then go back and darken your new line, skipping parts that overlap. You will also find that to make the letters pop she ads a shadow when a line in a letter overlaps. She's just erasing right beneath the overlapping line.
Suggested font: Engraver's Script
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